TIMEPIECE COMPONENT CONTAINING A HIGH-ENTROPY ALLOY

Abstract

The invention concerns a timepiece component containing a high-entropy alloy, the high-entropy alloy containing between 4 and 13 main alloying elements forming a single solid solution, the high-entropy alloy having a concentration of each main alloying element comprised between 1 and 55 at. %.

Claims

1: A timepiece component, comprising: a high-entropy alloy, wherein the high-entropy alloy is formed of multiple metallic elements forming a single-phase structure, and the high-entropy alloy satisfies formula Fe.sub.aMn.sub.bCo.sub.cCr.sub.d, or formula Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10, or formula Fe.sub.aMn.sub.bNi.sub.eCo.sub.cCr.sub.d, or formula Al.sub.aLi.sub.bMg.sub.cSc.sub.dTi.sub.e, where a, b, c, d, and e, when present, are each a value independently ranging from 1 to 55 at. %, and where x, when present, is a value ranging from 25 to 79 at. %.

2: The timepiece component according to claim 1, wherein the high-entropy alloy satisfies formula:
Fe.sub.aMn.sub.bCo.sub.cCr.sub.d, wherein a, b, c and d are from 1 to 55 at. %.

3: The timepiece component according to claim 1, wherein the high-entropy alloy satisfies formula:
Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10, wherein x is from 25 to 79 at. %.

4: The timepiece component according to claim 1, wherein the high-entropy alloy satisfies formula:
Fe.sub.aMn.sub.bNi.sub.eCo.sub.cCr.sub.d, wherein a, b, c, d and e are from 1 to 55 at. %.

5: The timepiece component according to claim 1, wherein the high-entropy alloy satisfies formula:
Al.sub.aLi.sub.bMg.sub.cSc.sub.dTi.sub.e, wherein a, b, c, d and e are from 1 to 55 at. %.

6: The timepiece component according to claim 1, wherein the high-entropy alloy comprises one or more interstitial elements selected from the group consisting of C, N, and B.

7: The timepiece component according to claim 1, wherein the high-entropy alloy comprises one or more structural hardening elements selected from the group consisting of Ti, Al, Be, and Nb.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features and advantages of the present invention will appear more clearly in the following detailed description of preferred embodiments, given by way of non-liming examples with reference to the appended Figures, in which:

[0026] 1 schematically represents a mainspring according to one embodiment of the invention;

[0027] FIG. 2 schematically represents the steps of a method for fabricating a mainspring according to one embodiment of the invention.

DETAILED DESCRIPTION

[0028] FIG. 1 schematically represents a mainspring 1 according to one embodiment of the invention. This mainspring 1 is made of a high-entropy alloy.

[0029] In such a high-entropy alloy, the entropy of mixing is high and makes the single phase more thermodynamically stable than the mixing of several phases.

[0030] The mainspring is preferably made from the high-entropy alloy described in the publication ‘Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off’, Zhiming Li et al, Nature 534, 227-230 (9 Jun. 2016). This high-entropy alloy has the following formula: Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10. x is preferably comprised between 25 and 79 at. %.

[0031] More precisely, according to a first embodiment, the mainspring may be made from a Fe.sub.35Mn.sub.45Co.sub.10Cr.sub.10 alloy. The mainspring produced in this manner has the advantage of combining high tensile strength and high ductility.

[0032] According to a second embodiment, the mainspring may be made from a Fe.sub.40Mn.sub.40Co.sub.10Cr.sub.10.alloy. The spring produced in this manner has the advantage of high tensile strength and high ductility. It also operates according to a TWIP (twinning induced plasticity) mechanism.

[0033] According to a third embodiment, the mainspring may be made from a Fe.sub.48Mn.sub.35Co.sub.10Cr.sub.10.alloy. The mainspring produced in this manner has the advantage of having even higher tensile strength and higher ductility. It also operates according to a TRIP (transformation induced plasticity) mechanism.

[0034] According to a fourth embodiment, the mainspring can be made from a Fe.sub.50Mn.sub.30Co.sub.10Cr.sub.10 alloy. The mainspring produced in this manner has the advantage of having even higher tensile strength and higher ductility. It operates according to a TRIP mechanism with the appearance of two phases, FCC and HCP, by a twinning mechanism.

[0035] The invention is not limited to fabrication of a mainspring. Indeed, other timepiece components could be fabricated from the high-entropy Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10 alloy, such as a spring, a staff, an impulse pin, a balance, an arbor, a roller, pallets, a pallet lever, a pallet fork, an escape wheel, a shaft, a pinion, a an oscillating weight, a winding stem, a crown, a jumper spring, a watch case, a bracelet link, a watch bezel, a bracelet clasp . . .

[0036] FIG. 2 schematically represents the steps of a method for fabricating the mainspring of FIG. 1.

[0037] This method includes a first step 101 of fabricating a high-entropy alloy ingot. To do so, the elements are mixed in pure or pre-alloy form, they are then melted, and the mixture is cast to form an ingot.

[0038] The method then includes a step 102 of hot forging the ingot.

[0039] The method then includes a hot lamination step 103.

[0040] The method then includes a cold lamination step 104.

[0041] The method then includes a wire drawing step 105.

[0042] The method then includes a cold lamination step 106.

[0043] Naturally, the invention is not limited to the embodiments described with reference to the Figures and variants could be envisaged without departing from the scope of the invention.

[0044] Thus, in the preceding examples, the Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10 alloy was used. However, other high-entropy alloys could be used, such as, for example: [0045] Fe.sub.20Mn.sub.20Ni.sub.20Co.sub.20Cr.sub.20, [0046] Fe.sub.40Mn.sub.27Ni.sub.26Co.sub.5Cr.sub.2, [0047] Ta.sub.20Nb.sub.20Hf.sub.20Zr.sub.20Ti.sub.20, [0048] Al.sub.20Li.sub.20Mg.sub.10Sc.sub.20Ti.sub.30, [0049] Cr.sub.18.2Fe.sub.18.2Co.sub.18.2Ni.sub.18.2Cu.sub.18.2Al.sub.9.0.